Post the MAC addresses that worked and didn't work (if you don't mind)

Yes, it works.

MAC Address is: 08:00:20:BB:08:9B
It can be added to the list by a manual editing of the configuration file.
This means:
- Backup current configuration.
- Edit the configuration file with a text editor.
- Restore the modified configuration file.

This is my own first Netgear router.
I think it has a lot of problem, this one is only the most obvious after 4 days of normal use.
Anyway, of course! It can be a standard function.
Other models can have different path or file name to javascript code.
Generally you can find it in html sources of their web interface.